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·Disclaimer: This blog post is based on a 2015 article chosen for the Lifelong Learning and Self Assessment (LLSA) for Emergency Physicians. This blog post is in no way designed to help facilitate passing of the LLSA exam. Rather, it highlights important literature flagged as relevant to clinical practice and is thus presented here as educational material for training residents. Clinical Question: In evaluating a patient with syncope, what exactly constitutes an abnormal EKG and what is the significance of these EKG findings in outcome?

Syncope is defined as a brief loss of consciousness with loss of postural tone, with eventual spontaneous and complete recovery without any medical intervention. Broad categories of causes of syncope include orthostatic-mediated syncope, neutrally mediated syncope and cardiovascular mediated syncope. Of the major causes of syncope, the latter group is the high risk patient population that needs to be identified by the Emergency Physician as studies have show a 6 month mortality of 10% without any intervention.[i] There are a lot of mimics of syncope, and often times, patients presentations may be hard to distinguish between true syncope and mimics. However, in my experience, I have noticed varying degrees of practice in patients presenting with syncope to the ED. Many studies have shown the large cost of workup of syncope patients including a large percentage of patients admitted to hospitals with benign causes of syncope. Many of these patients are worked up with extensive lab testing, imaging studies and admissions which have resulted in a calculated cost of workup for this subset of patients to be estimated at around $2 billion a year. [ii] Of all the workups we do in the ED, the EKG is perhaps the most important in risk stratifying our patients. This blog post highlights the following study:Quinn J, McDermott D. Electrocardiogram findings in emergency department patients with syncope. Acad Emerg Med. 2011;18(7):714-8. Design: This study looked at the EKG findings (which included EKGs, rhythm strips or any cardiac monitoring recorded) in a consecutive group of patients who presented with syncope and near syncope. Utilizing the definition of an abnormal EKG from the San Francisco Syncope Rule (any nonsinus rhythm or new EKG change), they analyzed the EKGs from their presenting patients. The patients were then followed for serious cardiac outcomes by day 7: death, myocardial infarction, arrhythmia thought to cause the syncope, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or any condition resulting a return to the ED and hospitalization or a therapeutic intervention for a related event. The EKG findings of these patients were analyzed to determine specific EKG findings that were associated with morbidly and mortality in patients presenting with syncope in their population studied. Finings: Of the 644 patients studied, 218 EKGs were flagged as abnormal as defined above. 42 patients suffered serious cardiac outcomes as defined above. In their analysis, they found that abnormal EKG criteria recognized 36 of the 42 patients. In their statistical analysis, the authors found that that by using the SFSR definition of an abnormal EKG, they were able achieve a sensitivity of 86%, specificity of 70% and a negative predictive value of 99% in predicting patients with cardiac outcomes. This led them to a conclusion that in a patient with a normal EKG as defined by the SFSR, the risk of significant cardiac outcome in the time frame studied was very low. In further statistical analysis of specific abnormal ekg findings, the authors were able to identify two specific findings with significant risk for adverse outcomes: any nonsinus rhythm and any conduction problem associated with the left bundle branch (LBBB, LAFB, LPFB or wide QRS). They had a calculated odds ratio of 2.8 and 3.2 for adverse cardiac outcome respectively. Finally, in their analysis of their patients, the authors found that utilizing EKGs only resulted in a significant amount of missing nonsinus rhythms when other rhythm strips were utilized in analysis. Relevance to Practice: This article does a good job of analyzing what the definition of an abnormal EKG is according to the SFSR. In their analysis, they were able to highlight the importance of negative EKG in the evaluation of patient presenting with syncope. While they did find a few high-risk findings on EKG predicting adverse outcomes, they do a good job of summarizing in their discussion section that the true utility of an abnormal EKG is hard to define. There is a wide variety of data on abnormal EKG findings and its relevance in adverse outcomes in patients presenting with syncope. Thus, it is important to understand that there is no agreement on what an abnormal ekg is in the setting of syncope and what the utility of an “abnormal” finding truly is. However, the EKG remains an important tool in evaluating patients presenting with syncope and near syncope, and the this study additionally shows us to utilize all data we have at our disposal in evaluating these patients, as an isolated EKG may miss abnormal findings caught elsewhere in evaluation.

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